/**
 * Copyright (C) 2002-2015   The FreeCol Team
 * <p>
 * This file is part of FreeCol.
 * <p>
 * FreeCol is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 * <p>
 * FreeCol is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * <p>
 * You should have received a copy of the GNU General Public License
 * along with FreeCol.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.sf.freecol.common.model;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.logging.Logger;

import javax.xml.stream.XMLStreamException;

import net.sf.freecol.common.io.FreeColXMLReader;
import net.sf.freecol.common.io.FreeColXMLWriter;


/**
 * Represents a production resource, such as prime tobacco, or an ore
 * vein, located on a Tile. A resource may be exhausted. In the
 * original game, only resources that produced silver were exhausted.
 */
public class Resource extends TileItem
{

    private static final Logger logger = Logger.getLogger( Resource.class.getName( ) );

    /** Some resources are unlimited. */
    private static final int UNLIMITED = - 1;

    /** The type of resource. */
    private ResourceType type;

    /** The amount of the resource present. */
    private int quantity;


    /**
     * Creates a standard <code>Resource</code>-instance.
     *
     * This constructor asserts that the game, tile and type are valid.
     *
     * @param game The enclosing <code>Game</code>.
     * @param tile The <code>Tile</code> on which this object sits.
     * @param type The <code>ResourceType</code> of this Resource.
     * @param quantity The quantity of resource.
     */
    public Resource( Game game, Tile tile, ResourceType type, int quantity )
    {
        super( game, tile );

        if ( type == null )
        {
            throw new IllegalArgumentException( "Parameter 'type' must not be 'null'." );
        }
        this.type = type;
        this.quantity = quantity;
    }

    /**
     * Creates a standard <code>Resource</code>-instance.
     *
     * This constructor asserts that the game, tile and type are valid.
     *
     * @param game The enclosing <code>Game</code>.
     * @param tile The <code>Tile</code> on which this object sits.
     * @param type The <code>ResourceType</code> of this Resource.
     */
    public Resource( Game game, Tile tile, ResourceType type )
    {
        this( game, tile, type, type.getMaxValue( ) );
    }

    /**
     * Creates new <code>Resource</code>.
     *
     * @param game The enclosing <code>Game</code>.
     * @param id The object identifier.
     */
    public Resource( Game game, String id )
    {
        super( game, id );
    }


    /**
     * Get the type of this resource.
     *
     * @return The resource type.
     */
    public ResourceType getType( )
    {
        return type;
    }

    /**
     * Is this an unlimited resource?
     *
     * @return True if this is an unlimited resource.
     */
    public boolean isUnlimited( )
    {
        return quantity == UNLIMITED;
    }

    /**
     * Get the resource quantity.
     *
     * @return The resource quantity.
     */
    public int getQuantity( )
    {
        return quantity;
    }

    /**
     * Set the resource quantity.
     *
     * @param newQuantity The new resource quantity.
     */
    public void setQuantity( int newQuantity )
    {
        quantity = newQuantity;
    }

    /**
     * Get the best goods type to produce here.
     *
     * @return The best goods type.
     */
    public GoodsType getBestGoodsType( )
    {
        return type.getBestGoodsType( );
    }

    /**
     * Reduce the available quantity by the bonus output of
     * <code>GoodsType</code>.
     *
     * @param goodsType The <code>GoodsType</code> to check.
     * @param unitType The producing <code>UnitType</code>.
     * @param potential The base potential of the tile.
     * @return The new quantity of resource.
     */
    public int useQuantity( GoodsType goodsType, UnitType unitType,
                            int potential )
    {
        // Return UNLIMITED here if not limited resource?
        return useQuantity( applyBonus( goodsType, unitType, potential )
                                    - potential );
    }

    /**
     * Reduces the available quantity.
     *
     * @param usedQuantity The quantity that was used up.
     * @return The final value of quantity.
     */
    public int useQuantity( int usedQuantity )
    {
        if ( quantity == UNLIMITED )
        {
            ; // No change
        }
        else if ( quantity >= usedQuantity )
        {
            quantity -= usedQuantity;
        }
        else
        {
            // Shouldn't generally happen.  Do something more drastic here?
            logger.severe( "Insufficient quantity in " + this );
            quantity = 0;
        }
        return quantity;
    }


    // Implement Named

    /**
     * {@inheritDoc}
     */
    @Override
    public String getNameKey( )
    {
        return getType( ).getNameKey( );
    }


    // Interface TileItem

    /**
     * {@inheritDoc}
     */
    @Override
    public final int getZIndex( )
    {
        return Tile.RESOURCE_ZINDEX;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isTileTypeAllowed( TileType tileType )
    {
        return tileType.canHaveResourceType( getType( ) );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int applyBonus( GoodsType goodsType, UnitType unitType,
                           int potential )
    {
        Set< Modifier > bonus = type.getModifiers( goodsType.getId( ), unitType );
        int amount = ( int ) applyModifiers( potential, null, bonus ) - potential;
        return potential
                + ( ( quantity == UNLIMITED || quantity > amount ) ? amount
                : quantity );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean canProduce( GoodsType goodsType, UnitType unitType )
    {
        if ( goodsType == null ) return false;
        // The presence of a resource can give a tile the ability to
        // produce a goods type.
        return ( int ) applyModifiers( 0f, getGame( ).getTurn( ),
                                       getProductionModifiers( goodsType, unitType ) ) > 0;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public List< Modifier > getProductionModifiers( GoodsType goodsType,
                                                    UnitType unitType )
    {
        return ( goodsType == null ) ? Collections.< Modifier >emptyList( )
                : new ArrayList<>( getType( )
                                           .getModifiers( goodsType.getId( ), unitType ) );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isNatural( )
    {
        return true;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isComplete( )
    {
        return true;
    }


    // Override FreeColGameObject

    /**
     * {@inheritDoc}
     */
    @Override
    public int checkIntegrity( boolean fix )
    {
        return ( type == null ) ? - 1 : 1;
    }


    // Serialization

    private static final String QUANTITY_TAG = "quantity";
    private static final String TILE_TAG = "tile";
    private static final String TYPE_TAG = "type";


    /**
     * {@inheritDoc}
     */
    @Override
    protected void writeAttributes( FreeColXMLWriter xw ) throws XMLStreamException
    {
        super.writeAttributes( xw );

        xw.writeAttribute( TILE_TAG, getTile( ) );

        xw.writeAttribute( TYPE_TAG, getType( ) );

        xw.writeAttribute( QUANTITY_TAG, quantity );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void readAttributes( FreeColXMLReader xr ) throws XMLStreamException
    {
        final Specification spec = getSpecification( );

        super.readAttributes( xr );

        tile = xr.findFreeColGameObject( getGame( ), TILE_TAG,
                                         Tile.class, ( Tile ) null, true );

        type = xr.getType( spec, TYPE_TAG,
                           ResourceType.class, ( ResourceType ) null );

        quantity = xr.getAttribute( QUANTITY_TAG, 0 );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String toString( )
    {
        return ( quantity == UNLIMITED ) ? getType( ).getId( )
                : Integer.toString( quantity ) + " " + getType( ).getId( );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String getXMLTagName( ) { return getXMLElementTagName( ); }

    /**
     * Gets the tag name of the root element representing this object.
     *
     * @return "resource".
     */
    public static String getXMLElementTagName( )
    {
        return "resource";
    }
}
